Large, elongate poles, often having a tapered shaft, are typically used as support structures for utility lines, billboards, large area lighting, antenna systems, and so forth. These poles sometimes need to be removed for any number of reasons. For example, when utilities are being placed underground or when an electrical line is being decommissioned, the poles are removed so that the land can be reclaimed for another purpose, such as for building roadways. The old poles may also be replaced when the poles have lost structural integrity.
When a pole, embedded in the earth and used as a support structure, needs to be removed, a pole puller is sometimes utilized. This device typically includes a hydraulic cylinder mounted to a base, with the cylinder aligned vertically adjacent the pole to be removed. The cylinder is affixed to the pole with a chain wrapped around the pole. Repeated actuations of the cylinder permit the pole to be extracted in small increments. Once the pole is extracted, the pole may be reused or discarded.
When used with a wooden pole, the links of the chain tend to bite into a wood to largely prevent the chain from rolling or slipping. Unfortunately, when such an apparatus is used to remove a steel pole, the chain cannot readily bite into the steel. Thus, the chain may slip, thereby making extraction of steel poles very difficult. If the chain is forced tight enough to bite into the steel, the hoop strength of the steel pole may be compromised. Hoop strength is a physical property that describes the ability of a tube, in this case the steel pole, to withstand internal pressure, bending force, and crushing force. Accordingly, if the hoop strength of the steel pole is compromised, the pole may be more likely to fail when a load is placed on the pole, leading to potentially costly equipment damage and significant safety issues.
Another problem with the use of pole pullers is that the chain must be loosened from the pole by a workman along with each downward (return) stroke of the cylinder. The workman must then work the chain down the pole prior to each upward stroke of the cylinder. Obviously, such activity increases the time required for pole extraction. Moreover, such activity is hazardous for the workman whose task it is to manipulate the chain. Indeed, fingers have been broken and even amputated due to the tension imposed on the chain by the pole puller.
For the reasons discussed above, the use of a pole puller with a chain has not previously been suitable for the removal of a steel pole. Therefore, excavation around the pole to the bottom, or butt, of the pole has been adopted as an alternative technique for pole removal. Once excavation is complete, the pole can then be pulled out with the boom on a boom truck. Unfortunately, such a technique is costly, due to the undesirably long time it takes to excavate and remove a single pole, due to the costly digging equipment needed to remove a steel pole, and due to the likelihood of damage to the pole by the excavating equipment. In addition, while this method may work satisfactorily in rural areas, it presents many problems and hazards if attempted in an urban setting, where underground utilities, pavement, etc., can limit its use. Also, after having extracted a pole by this means, it is thereafter difficult to insure that a new pole placed in the original hole will be firmly held in place, as the hole is, in effect, twice as big as was necessary.
Another method for removing old poles involves the use of a boom truck. The boom truck is backed up to the pole to be removed, and the boom is secured to the pole. By making repeated upward jerks with the boom, some poles, if not too tightly embedded, could be removed. However, this method is extremely disadvantageous in that it places severe stress on the most expensive equipment typically owned by utility or sign companies—the boom truck. In particular, with repeated use, the boom tends to bend or break at the interface between the boom and the truck bed. In addition, winch lines can snap, causing equipment damage and/or personnel injury.
Faced with these difficulties, some companies have chosen to cut off the pole and leave a “butt” in place, finding it to be less expensive to purchase a new pole rather than attempting to extract the old pole and reuse it. This is obviously a wasteful practice, since the pole cannot then be reused. In addition, environmental concerns arise when leaving a treated wooden pole “butt” in place. With regard to steel poles, companies and the general public may find it quite unacceptable to cut off a steel pole and leave the steel pole “butt” in place. As such, this practice is not a viable option if a reasonably practicable alternative is available.
Accordingly, what is needed is a mechanism for facilitating safe and economical removal of old poles, especially of steel poles.